AbstractThe history of chemical health hazards in the work environment is traced from prehistoric times to the present day. Early hazards included toxins from plant, animals, and sometimes minerals. Later, the most hazardous conditions were for miners and mineral processors, dyers, potters, etc.The first health-at-work legislation limited working hours in Spain's mercury mines from 1665. Serious attempts to identify and combat these health risks were first made on a significant scale late in the last century.Technology is now available to improve greatly the possibility of reducing harmful effects, despite the increased complexity of recent chemical hazards.